Stem growth and canopy dynamics in a world-wide range of Fagus forests

Abstract. Forests dominated by Fagus (beech) occur widely in the Northern Hemisphere. Tree species dominant together with beech vary in tolerance of understorey conditions. They are deciduous broad-leaved, evergreen broad-leaved or evergreen coniferous. The frequency and intensity of events that reduce the forest canopy cover are important determinants of the ratio of beech to other species in the canopy. For trees in the understorey and the canopy, stem diameter growth rate is determined by light regime and growing space which in turn are determined by canopy cover. We evaluated increase in stem diameter growth rate as an indicator of sudden reductions in canopy cover and canopy dynamics. We used tree-ring chronologies and calculated an index of growth rate increase (GI) to compare the canopy dynamics of 11 natural beech forests. Per site, the annual average value of GI poorly reflected the effects of dry or cool summers, and it clearly reflected events like tornados and hurricanes that removed substantial canopy cover. Among groups of sites average values of GI were significantly different. In the sites with a lower level of average GI, the establishment of the more shade tolerant tree and shrub species in the understorey was favoured, and subcanopy layers became more dense. On the other hand, higher levels of average GI allowed for more light demanding tree species to reach the canopy.     

Differences in beech (Fagus crenata) regeneration between two types of Japanese beech forest and along a snow gradient

Differences in beech (Fagus crenata) regeneration were quantitatively investigated using power function analysis for the size–class (diameter at breast height, DBH) distribution and juvenile-to-canopy tree (J/C) ratio along a snow gradient throughout Japan. In snowy areas, all species combined, as well as F. crenata alone, showed constant regeneration, with parameter b≈−1.6 for the power function y=ax ^b (x=DBH, y=density), which is related to the DBH–class distribution. The good fit of the data to the function suggests that beech regenerates constantly with self-thinning patch dynamics. Parameter a, which indicates the abundance of small trunks, was high. Furthermore, the mean J/C ratio was ≈8, i.e., each parent beech tree produced eight juveniles. These results suggest that beech regenerates constantly with gap dynamics in snowy beech forests on the Japan Sea side of Japan (snowy). However, the fit of F. crenata was lower and nonsignificant in some forests in less snowy areas, despite the high fit of all species combined. In these areas, the mean of a was low, and b was often near zero for F. crenata regressions. These results suggest that the abundance of beech was low, and self-thinning was not evident because of the initial low abundance. Moreover, the mean J/C ratio was <1.0, suggesting that juvenile density was lower than that of canopy trees. Thus, the regeneration of F. crenata on the Pacific Ocean side of Japan (less snowy) is rather sporadic. Less snowy conditions may promote seed desiccation, predation of beechnuts and seedlings, and water stress. Lower F. crenata density may also reduce predator satiation and wind pollination.     

Regeneration dynamics, causal factors, and characteristics of pacific ocean-type beech (Fagus crenata) forests in Japan: A review

This paper reviews the differences in the distribution and regeneration ofFagus crenata between two types of Japanese beech forests, the Japan Sea (JS)-type and the Pacific Ocean (PO)-type, and discusses the causal factors and characteristics of these forests, particularly the PO-type.F. crenata in PO-type forests regenerates sporadically rather than constantly, whereas regeneration in the JS-type forests is relatively constant with gap dynamics.F. crenata has dominated in snowy areas both in the past, after the last glacial age, when there was less human disturbance, and in the present. Snow accumulation facilitates beech regeneration in snowy JS-type forests, but not in the less snowy PO-type. Snow protects beechnuts from damage caused by rodents, desiccation, and freezing. In addition, snow suppresses dwarf bamboo in the spring, thus increasing the amount of sunlight available for beech seedlings on the forest floor. Snow also supplies melt water during the growing season and limits the distribution of herbivores. Moreover, snow reduces the number of forest fires during the dry winter and early spring seasons. The low densities ofF. crenata impede its regeneration, because disturbed wind pollination lowers seed fertility and predators are less effectively satiated. In snowy JS-type beech forests,F. crenata dominates both at the adult and the juvenile stages because it regenerates well, while other species are eliminated by heavy snow pressure. On the less snowy PO-side, deciduous broad-leaved forests with various species are a primary feature, althoughF. crenata dominates because of its large size and long lifespan.     

Spatial dynamics of regeneration in a conifer/broad‐leaved forest in northern Japan

Abstract. This study deals with stand dynamics over a 6‐yr period in a conifer/broad‐leaved mixed forest in Hokkaido, northern Japan. The annual rates of gap formation and recovery were 81.3 m²/ha and 66.7 m²/ha, respectively and turnover time of the canopy was 125 yr. The recruitment processes of the component species in this cool‐temperate forest were governed by different canopy types: gap, canopy edge and closed canopy. Magnolia obovata regenerated in canopy edges, and Acer mono and Prunus ssiori regenerated in canopy edges and gaps. The results suggested that the mosaic structure made up of closed canopy, canopy edge and gap was related to various regeneration niches. Abies sachalinensis had high mortality rates, initiating gap expansion. The transition probabilities from closed canopy or canopy edge to gap for deciduous broad‐leaved trees were lower than for A. sachalinensis, which implies that the difference in degeneration patterns of conifer and broad‐leaved canopies contributes to the heterogeneity of spatial structure in the mixed forests. Spatial dynamics were determined by a combination of gap expansion by A. sachalinensis (neighbour‐dependent disturbance) and gap formation by deciduous broad‐leaved trees (random disturbance).     

Natural disturbance and tree species coexistence in an old-growth beech - dwarf bamboo forest,southwestern Japan

Abstract. The structure and composition of a cool-temperate old-growth beech (Fagus crenata) - dwarf bamboo (Sasa spp.) forest, partially affected by landslide disturbance, in the Daisen Forest Reserve of southwestern Japan, were investigated in relation to forest floor and canopy conditions. All stems ≥ 4 cm DBH were mapped on a 4-ha plot and analyses were made of population structure, spatial distribution and spatial association of major tree species. The dominant species, F. crenata, which had the maximum DBH among the species present, had the highest stem density. However, for other species, larger-sized species had lower stem density with few smaller stems or saplings, while smaller-sized species had higher stem density with many smaller stems or saplings. Canopy trees of F. crenata were distributed randomly in the plot, while its stems in the other layers and all other species were distributed patchily. Small patches represent gap-phase regeneration. Larger patches correlate with landslide disturbance, difference in soil age, or the presence/absence of Sasa. Cluster analysis for spatial associations among species and stems in the different layers revealed that the forest community consists of several groups. One main group was formed on sites not covered with Sasa. This group contained a successional subgroup (from Betula grossa to Acer mono and/or F. crenata) initiated by landslide disturbance and a subgroup of tree species that avoid Sasa. Another group was formed on sites with mature soils covered largely with Sasa. This contained associations of canopy trees of F. crenata and smaller-sized tree species such as Acanthopanax sciadophylloides and Acer japonicum. It is found that the community of this old-growth beech forest is largely organized by natural disturbance and heterogeneous conditions of the forest floor (difference in soil age and presence/absence of Sasa). The existence of these different factors and the different responses of species to them largely contribute to the maintenance of tree species diversity in this forest.; Keywords: Cluster analysis; Fagus crenata; Forest dynamics; Gap; Landslide; Spatial pattern.     

Regeneration of beech (Fagus crenata) after the simultaneous death of undergrowing dwarf bamboo (Sasa kurilensis)

Seedling recruitment and survivorship of beech (Fagus crenata) were studied with special reference to the simultaneous death of undergrowing bamboo (Sasa kurilensis). The survival rate of beech seedlings on the floor whereSasa had withered was much higher than that on the floor whereSasa survived. Damping off caused the largest mortality among beech seedlings. However, the allocation pattern of matter to different parts of the seedlings indicated that their survival was greatly affected by production economy. The dense cover of dwarf bamboo prevented the establishment of beech seedling banks on the forest floor. The interval between the times when simultaneous death ofSasa occur and the length of its recovery period are thus important factors controlling the dynamics of beech forests in Japan.     

Mitochondrial DNA Variation Follows a Geographic Pattern in Japanese Beech Species

The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re-evaluation of their phylogenetic relationships.     

Dendrochronological analysis of the canopy history of two Ohio old-growth forests

This study examined the temporal patterns of establishment, suppression, and release of major tree species in two old-growth Ohio forest remnants as a means to determine the past disturbance history of these forests. Increment cores were taken from a total of 154 trees from two well-drained, upland plots and two poorly-drained, bottomland plots in each of the two forested areas. Acer saccharum and Fagus grandifolia exhibited multiple episodes of suppression and release prior to becoming canopy trees, and could tolerate suppressions as long as 84 years. In contrast, Quercus macrocarpa, Q. muehlenbergii, Prunus serotina, and Acer saccharinum rerely exhibited any tolerance to suppression and appeared to have entered the canopy after single disturbances had opened large areas of canopy. There was clear synchrony in the temporal pattern of establishment and final release from suppression among trees from bottomland plots scattered throughout the stands, indicating that relatively large disturbances were important in these poorly-drained areas. In contrast, there was little synchrony among trees from well-drained upland plots, except in a single instance where selective cutting of Quercus trees opened the canopy. Thus, the canopy of upland site was likely subjected only to small disturbances resulting from the death of one or a few trees. At the whole of forest level, there was evidence of episodic recruitment of canopy trees in both forests. Establishment of Fraxinus spp. and Quercus spp. were particularly episodic, and few Fraxinus or Quercus trees alive today established during the last century. These data suggest that large disturbances have affected canopy dynamics of both upland and bottomland areas prior to 1900 and in bottomland forests through this century. In contrast, disturbances in upland areas during this century have been restricted to small, treefall-generated canopy gaps.     

Disturbance history and tree establishment in old-growth Pinus koraiensis-hardwood forests in the Russian Far East

Abstract. Dendro-ecological studies were undertaken to document the disturbance history in two old-growth mixed Pinus koraiensis-hardwood forests in the southern part of the Sikhote-Alin mountains in the Russian Far East. Establishment of four common canopy conifers, Abies holophylla, A. nephrolepis, P. koraiensis and Picea ajanensis, and three common canopy hardwoods, Acer mono, Betula costata and Tilia amurensis, were also inferred from population age structures and spatial dispersion patterns. Growth releases on increment cores suggested that peak periods of growth releases indicating partial canopy disturbances have repeatedly occurred over the past 230 yr at intervals from ca. 35 to 100 yr. Slight releases and suppressions other than the peak releases occurred in many years of both histories, suggesting the formation of smaller-scale canopy gaps. Despite the predominance of anthropogenic fires in Primorskiy Kray at present, destructive fires had not affected either forest. Wind disturbances and low intensity fires are likely factors controlling the dynamics of the forests. Under the disturbance regime, P. koraiensis has maintained its populations through its dependence on canopy gaps for establishment. Age distribution and gap dependence of P. ajanensis, A. nephrolepis and A. mono suggested continuous establishment of these species under a closed canopy, whereas occasional establishment of T. amurensis was derived largely from vegetative reproduction. Restricted establishment of A. holophylla and B. costata suggested a variety in kinds of disturbance throughout the histories. Continuous habitation of the study area by P. koraiensis is likely under the disturbance regime without destructive fires.     

Shoot dynamics and architecture of saplings in Fagus crenata across its geographical range

 Relationships between leaf or shoot size, number, and arrangement in response to light were investigated to test the hypothesis that these characteristics are linked. In order to test this hypothesis, the divergence in allometry and shoot dynamics in saplings of Japanese beech (Fagus crenata) obtained from four populations and having different leaf sizes were examined in a nursery under both full sun and shade conditions. Trees with different leaf sizes also showed large differences in canopy structure, particularly when shade-grown saplings were compared. The final leaf mass distributions of the large-leaf populations were conical or “bottom - heavy”, while those of the small-leaf populations were planar or “top - heavy”. The slope of the allometric relations between leaf mass and shoot and branch mass in small-leaved populations were steeper than those in large-leaf populations. The four populations were classified into two growth types: populations producing a few large leaf and shoot modules corresponded to “stem growth type”, and those producing many small leaf and shoot modules corresponded to “leaf growth type”. These kinds of intra-specific variation in architecture and growth of F. crenata trees may influence the structure and dynamics of forests in accordance with differences in competitive ability or sensitivity to disturbances such as windstorm. Received: 18 March 1997 / Accepted: 21 October 1997     

Impact of a strong typhoon on the structure and dynamics of an old-growth beech (<Emphasis Type="Italic">Fagus crenata</Emphasis>) forest,southwestern Japan

Typhoon no. 19 of 1991 (T9119) caused multiple treefalls and created large openings in an old-growth beech (Fagus crenata) forest at Mt. Daisen, in the Daisen Forest Reserve, southwestern Japan. The area of the largest opening was about 1.7 ha (300 m by 70 m). To predict the dynamics of the beech stand after the disturbance of T9119, we investigated the damage to the stand and the density and growth rate of trees with DBH=5–10 cm in a 1-ha plot covering a large part of the largest opening and the adjacent closed canopy. The beech did not regenerate immediately. The regeneration and growth rate of trees with DBH=5–10 cm were related to the frequency of the typhoon attack for at least the past century. In beech forests, small gap formation is the prevailing mode of disturbance. Our results indicate that typhoons affect the structure and dynamics of this beech stand. We suggest that both small gap formation and large-scale disturbance are important for the maintenance of beech forest in some areas.     

Gap regeneration of major tree species in different forest types of Japan

Gap regeneration of major tree species was examined, based on the pattern of gap phase replacement, in primary old-growth stands of warm-temperate, cool-temperate and subalpine forests, Japan. Using principal component analysis, the gap-regeneration behavior of major tree species could be divided into three guilds and that of Fagus crenata (monodominant species of cool-temperate forests). The criteria used for this division were total abundance of canopy trees and regenerations and relative abundance of regenerations to canopy trees. The gap-regeneration behavior of species in the first guild was that canopy trees regenerate in gaps from seedlings or saplings recruited before gap formation; they had higher total abundance and more abundant regenerations relative to their canopy trees. The gap-regeneration behavior of F. crenata was same as species in the first guild, but F. crenata had less abundant regenerations relative to its canopy trees. Species in the second guild had lower total abundance and less abundant regenerations to their canopy trees. The guild contained species whose canopy trees regenerate in gaps from seedlings or saplings recruited after gap formation or regenerate following largescale disturbance. The third guild consisted of species with lower total aboundance and more abundant regenerations relative to their canopy trees. The gap-regeneration behavior of some species in this guild was that trees regenerate in gaps from seedlings or saplings recruited before gap formation, and grow, mature, and die without reaching the canopy layer, while the gap-regeneration behavior of other species was same as that of species in the first guild or F. crenata. Major tree species of subalpine forests were not present in the third guild.     

Species diversity of Chinese beech forests in relation to warmth and climatic disturbances

The trends in the occurrence of climatic disturbances in the ChineseFagus range are described, and the relationship between woody species diversity and climatic factors in eight old-growth Chinese beech forests is characterized. In the ChineseFagus range that lies in the humid mountains of southern China, wind storms and heavy rain frequency increase towards the eastern coast. Thunderstorm frequency increases southwards. Snowfall frequency increases northwards. Glaze storm frequency peaks in the center near Lake Dongtian, but much higher in the east than in the west. Hailstorm frequency also peaks in the center. The forests sampled in this study are widely separated. Their canopies consist of either deciduous broad-leaved trees or a mixture of evergreen and deciduous broad-leaved trees. Their species diversity increases towards warmer sites and towards the east. The importance of the evergreen trees in relation to warmth and minimum temperature increases southwards. Our analysis suggests that wind storms and heavy rains enhance the species diversity of Chinese beech forests. Cold disturbances such as glaze and snow diminish the diversity and canopy dominance of evergreen broad-leaved trees but favor deciduous broad-leaved trees, especially beech. The annual precipitation received by the forests in this study varies from 1400–2550 mm. This is not correlated with diversity, however, probably because all of these forests grow in humid conditions with sufficient water being supplied by precipitation throughout the year.     

Dynamics of forests with Araucariaceae in the western Pacific

Abstract. Several species of Araucaria and Agathis (Araucariaceae) occur as canopy emergents in rain forests of the western pacific region, often representing major components of total stand biomass. New data from permanent forest plots (and other published work) for three species (Araucaria hunsteinii from New Guinea, A. laubenfelsii from New Caledonia, and Agathis australis from New Zealand) are used to test the validity of the temporal stand replacement model proposed by Ogden (1985) and Ogden & Stewart (1995) to explain the structural and compositional properties of New Zealand rain forests containing the conifer Agathis australis. Here we propose the model as a general one which explains the stand dynamics of rain forests with Araucariaceae across a range of sites and species in the western Pacific. Forest stands representing putative stages in the model were examined for changes through time in species recruitment, growth and survivorship, and stand richness, density and basal area. Support for the model was found on the basis of: 1. Evidence for a phase of massive conifer recruitment following landscape-scale disturbances (e.g. by fire at the Huapai site, New Zealand for Agathis australis); 2. Increasing species richness of angiosperm trees in the pole stage of forest stand development (i.e. as the initial cohort of conifers reach tree size; >10 cm DBH); 3. A high turnover rate for angiosperms (<100 yr), and low turnover for conifers (≥ 100 yr) in the pole stage, but similar turnover rates for both components (50–100 yr) as forests enter the mature to senescent phase for the initial conifer cohort; 4. Very low rates of recruitment for conifers within mature stands, and projected forest compositions which show increasing dominance by angiosperm tree species; 5. A low probability of conifer recruitment in large canopy gaps created by conifer tree falls during the initial cohort senescent phase, which could produce a second generation low density stand in the absence of landscape scale disturbance; 6. Evidence that each of the three species examined required open canopy conditions (canopy openness > 10 %) for successful recruitment. The evidence presented here supports the temporal stand replacement model, but more long-term supporting data are needed, especially for the phase immediately following landscape level disturbance.     

The limited role of canopy gaps in the successional dynamics of a mature mixed Quercus forest remnant

Question: Are canopy gap dynamics responsible for driving the structural and compositional changes that have occurred over a 26‐year period in a mature Quercus forest remnant? Location: Dobbs Natural Area, an unlogged 3.6‐ha forest preserve in west‐central Indiana, USA. Methods: We analyzed mapped permanent plot data for a site that illustrates a trend common in Quercus‐dominated forests in eastern North America, where recruitment of new stems is dominated by mesophytic, shade‐tolerant species such as Acer saccharum, rather than Quercus. We developed a GIS database from stand census measurements taken in 1974 and 2000, employing it to conduct tree‐by‐tree comparisons that allow direct determination of ingrowth, mortality and survivorship, and to relate the spatial patterns of subcanopy dynamics to canopy gap occurrence. Results: The re‐census shows modest changes in canopy composition, but much greater turnover in the subcanopy. Nearly half of all individuals originally present died; much of this mortality resulted from a major decline in subcanopy Ulmus americana. While overall density remained fairly constant, the subcanopy experienced substantial ingrowth of shade‐tolerant Acer saccharum, Fagus grandifolia, and Tilia americana. Canopy gaps, although forming at rates in the upper range of regional averages, did not significantly benefit subcanopy populations of Quercus spp. or most other taxa with limited shade tolerance. Conclusions: Canopy gaps play a minor role in driving the recent demographic trends of this stand. The spatial and temporal scales of light availability in gaps do not support regeneration of most shade‐intolerant species. Compositional change parallels a historical shift in light regimes.     

Differentiation and maintenance of topo-community patterns with reference to regeneration dynamics in mixed cool temperate forests in the Chichibu Mountains,central Japan

Topo-community structure and dynamics were studied in mixed cool temperate forests, using the regeneration dynamics, to clarify the maintenance mechanisms of community patterns along a microtopographic gradient. The 76 stands studied were classified into two groups (i.e. convex slope and concave slope stands). The soil surface was more eroded on the concave slope than on the convex slope, while water potential was not significantly different between topographies. On the convex slope, even-aged patches alternated between young phase patches dominated by shade intolerant species, such asAcer rufinerve andBetula grossa, and mature phase patches, withTsuga sieboldii andFagus crenata. A slower lateral growth rate ofTsuga canopy trees and the absence of suppressed saplings in the mature phase may prolong the gap phase, which provides a favorable situation to shade-intolerant species. On the concave slope, patch structure was less clear, and process of replacement of canopy species by previously suppressed individuals of the same species was seen in the mature phase, which was mainly composed ofF. crenata, Fagus japonica, Acer sieboldianum andStewartia pseudo-camellia. Gaps on the concave slope were formed frequently but were generally closed within 10 years by lateral growth of deciduous canopy trees and by upgrowth of suppressed trees, and thus some individuals underwent recurrent periods of suppression until they reached the canopy. We concluded that soil surface stability and gap encroachment pattern are critical to the maintenance of the community pattern along a microtopographic gradient.     

Structure,dynamics and disturbance regime of temperate broad-leaved forests in Japan

Abstract. Structure, diversity and dynamics of five Japanese temperate old-growth forests were compared, differing from each other in, i.a., climate, dominant tree type, topography, disturbance regime. The forests were Aya, Ogawa, Kanumazawa Riparian, Kanumazawa upland and Senju. A permanent plot (1–6 ha) was established in each forest and trees were censused several times at intervals of two years. Mean annual recruitment rates and mortality rates in these forests were both in the range of 0.5 to 4.6 %/yr at the community level. Analyses of the structure and dynamics of populations showed that the underlying process was different among the forests. Some forests experienced compositional shifts in their canopies, others had a constant canopy composition but appeared to lack effective regeneration in recent years. The recruitment rate appeared to be strongly affected by competitive undergrowth vegetation such as dwarf bamboo which has been controlled by natural disturbance or human impact. It is likely that the forests with mostly low recruitment rates had a low species diversity. The current variation in structure, diversity and dynamics of the studied forests might have been determined not only by physical conditions (e.g. climate) but also by chance factors (e.g. disturbance, outbreak of deer population).     

Determinants of woody species richness in Scot pine and beech forests: climate, forest patch size and forest structure

We analysed patterns of woody species richness in Pinus sylvestris and Fagus sylvatica forests in Catalonia (NE Spain) from forestry inventory databank in relation to climate and landscape structure. Both types of forests are found within the same climatic range, although they have been managed following somewhat different goals. Overall, woody species richness significantly increased when conditions get closer to the Mediterranean ones, with milder temperatures. Differences between the two types of forests arose when comparing the relationship between richness and forest patch size. Woody species richness increased in pine forests with patch size, while the opposite trend was observed in beech forests. This pattern is explained by the different behaviour of structural canopy properties, since leaf area index and canopy cover showed a steeper increase with increasing forest patch size in Fagus forests than in Pinus ones. Accordingly, richness decreased with canopy cover in Fagus plots, but not in Pinus ones. We suggest that these differences would be related to management history, which may have enhanced the preservation of beech stands in larger forest landscape units.     

Establishment of Fagus sylvatica and Fraxinus excelsior in an old-growth beech forest

Abstract. Distribution of tree seedlings, forest architecture, light conditions, ground vegetation and humus conditions were studied in a 45 m × 100 m area including multiple gaps in an old-growth beech forest. Gaps were created after some beech trees had been felled in severe storms in February 1990. A group of adult ash trees is found near the study site. The data were analyzed by Correspondence Analysis. Young seedlings (< 4 yr), of both Fraxinus (a sun species) and Fagus (a shade species), were most abundant under the crown of beech trees in semi-shade conditions, and where beech litter did not accumulate. Differences in the dissemination of Fraxinus and Fagus explained differences in the establishment of the two species. In contrast, older seedlings of beech established before the storms were more numerous in the gaps, suggesting a change in the ecological requirements of beech seedlings in the course of time.     

Population dynamics of four understorey shrub species during a 7‐yr period in a primary beech forest

Abstract. Shrubs persist in the understorey layer of forests throughout their lives, while tall trees remain there only during the juvenile stage and then grow into the canopy layer. Thus demographic parameters (recruitment‐, mortality‐, and growth‐rates) of shrub species are expected to differ from those of tall tree species. We investigated aspects of the demography of four dominant deciduous‐shrub species (Viburnum furcatum, Lindera umbellata var. membranacea, Magnolia salicifolia, and Hydrangea paniculata) in Fagus crenata forests at the beginning and at the end of a 7‐yr period in a 1‐ha permanent plot. For each species, the number of stems changed little (within ± 10%) during the study period, while total basal area increased markedly (11.7–33.8%), because (1) new stems continuously recruited by vegetative growth replaced the substantial number of dead stems, and (2) vegetative stems grew vigorously, probably due to nutrient support from parents. The results indicate that these four understorey shrub species have high ability to maintain their population size in the shaded forest understorey. While in each species more than half of the dead stems were standing dead, a substantial proportion of the dead stems (9.0–38.5%) showed signs of mechanical damage, such as stem breakage and suppression by fallen branches or trees. Snow pressure that resulted in decumbent stems was also an important mortality agent for V. furcatum (20.7%) and L. umbellata var. membranacea (5.6%). Probability of damage was constant across all DBH‐classes for all study species. In each species, newly recruited stems and dead stems were spatially aggregated, largely due to habits of vegetative growth and mechanical damage, respectively. This study revealed that several demographic traits, resulting from recruitment by vegetative growth and death by mechanical damage, were shrub‐species specific and markedly different from those of tall tree species.